package com.codeforces.cf584;

import java.util.Scanner;

public class A {
    Scanner in  = new Scanner(System.in);
    void solve(){
        int t = in.nextInt();
        while(t-- > 0){
            int n = in.nextInt();
            int c0 = in.nextInt(),c1 = in.nextInt();
            int h = in.nextInt();
            String str = in.next();
            int a = helper(str);
            int b = n - a;
            int res = a * c0 + b * c1;
            res = Math.min(res,b * c1 + a * c1 + a * h);
            res = Math.min(res,a * c0 + b * c0 + b * h );
            System.out.println(res);
        }
    }
    int helper(String s){
        int count = 0;
        for(char ch : s.toCharArray()){
            if(ch == '0'){
                count++;
            }
        }
        return count;
    }
    public static void main(String[] args) {
        A s = new A();
        s.solve();
    }
}
